package admin

import (
	"database/sql"
	"errors"
	"net/http"

	"git.asio.asia/nixevol/NixMsg/internal/auth"
	"git.asio.asia/nixevol/NixMsg/internal/httpx"
)

func (h *Handler) setSessionCookie(w http.ResponseWriter, r *http.Request, value string, maxAge int) {
	secure := h.forceSec || httpx.IsHTTPS(r, h.trusted)
	http.SetCookie(w, &http.Cookie{
		Name:     cookieName,
		Value:    value,
		Path:     "/",
		HttpOnly: true,
		SameSite: http.SameSiteLaxMode,
		Secure:   secure,
		MaxAge:   maxAge,
	})
}

func (h *Handler) handleLogin(w http.ResponseWriter, r *http.Request) {
	ip := httpx.ClientIP(r, h.trusted)
	if locked, retry := h.locks.Check(auth.LockKey{Kind: auth.LockAdminIP, IP: ip}); locked {
		w.Header().Set("Retry-After", formatRetryAfter(retry))
		httpx.WriteError(w, http.StatusTooManyRequests, "rate_limited", "登录已锁定，请稍后再试")
		return
	}

	var req struct {
		Username string `json:"username"`
		Password string `json:"password"`
	}
	if err := httpx.DecodeJSON(r, &req); err != nil {
		httpx.WriteError(w, http.StatusBadRequest, "bad_request", "请求体无效")
		return
	}
	if req.Username != adminUsername {
		h.failLogin(w, ip)
		return
	}

	phc, err := h.getAdminPasswordHash(r.Context())
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			h.failLogin(w, ip)
			return
		}
		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	ok, err := h.hash.Verify(r.Context(), auth.PasswordAdmin, req.Password, phc)
	if err != nil || !ok {
		h.failLogin(w, ip)
		return
	}

	h.locks.Clear(auth.LockKey{Kind: auth.LockAdminIP, IP: ip})

	plain, hashHex, err := newSessionToken()
	if err != nil {
		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	if err := h.createSession(r.Context(), hashHex, h.ttl); err != nil {
		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	h.setSessionCookie(w, r, plain, int(h.ttl.Seconds()))
	h.audit("admin", "login", "", "ok", ip)
	httpx.WriteOK(w, map[string]any{"username": adminUsername})
}

func (h *Handler) failLogin(w http.ResponseWriter, ip string) {
	locked, retry := h.locks.Fail(auth.LockKey{Kind: auth.LockAdminIP, IP: ip})
	if locked {
		w.Header().Set("Retry-After", formatRetryAfter(retry))
		httpx.WriteError(w, http.StatusTooManyRequests, "rate_limited", "登录已锁定，请稍后再试")
		return
	}
	httpx.WriteError(w, http.StatusUnauthorized, "unauthorized", "用户名或密码错误")
}

func (h *Handler) handleLogout(w http.ResponseWriter, r *http.Request) {
	p, _ := principalFrom(r.Context())
	ip := httpx.ClientIP(r, h.trusted)
	if p.Kind == authCookie && p.Session != "" {
		_ = h.deleteSession(r.Context(), hashSessionHex(p.Session))
	}
	h.setSessionCookie(w, r, "", -1)
	h.audit(actorString(p), "logout", "", "ok", ip)
	httpx.WriteOK(w, map[string]any{})
}

func (h *Handler) handleMe(w http.ResponseWriter, r *http.Request) {
	p, _ := principalFrom(r.Context())
	authMode := "cookie"
	if p.Kind == authToken {
		authMode = "token"
	}
	httpx.WriteOK(w, map[string]any{
		"username": adminUsername,
		"auth":     authMode,
	})
}

func (h *Handler) handlePassword(w http.ResponseWriter, r *http.Request) {
	p, _ := principalFrom(r.Context())
	ip := httpx.ClientIP(r, h.trusted)

	var req struct {
		OldPassword string `json:"old_password"`
		NewPassword string `json:"new_password"`
	}
	if err := httpx.DecodeJSON(r, &req); err != nil {
		h.audit(actorString(p), "password_change", "", "bad_request", ip)
		httpx.WriteError(w, http.StatusBadRequest, "bad_request", "请求体无效")
		return
	}
	if len(req.NewPassword) < minPasswordLen {
		h.audit(actorString(p), "password_change", "", "bad_request", ip)
		httpx.WriteError(w, http.StatusBadRequest, "bad_request", "新密码至少 12 位")
		return
	}

	phc, err := h.getAdminPasswordHash(r.Context())
	if err != nil {
		h.audit(actorString(p), "password_change", "", "error", ip)
		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	ok, err := h.hash.Verify(r.Context(), auth.PasswordAdmin, req.OldPassword, phc)
	if err != nil || !ok {
		h.audit(actorString(p), "password_change", "", "unauthorized", ip)
		httpx.WriteError(w, http.StatusUnauthorized, "unauthorized", "旧密码错误")
		return
	}
	newPHC, err := h.hash.Hash(r.Context(), auth.PasswordAdmin, req.NewPassword)
	if err != nil {
		h.audit(actorString(p), "password_change", "", "error", ip)
		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	if err := h.setAdminPasswordHash(r.Context(), newPHC); err != nil {
		h.audit(actorString(p), "password_change", "", "error", ip)
		httpx.WriteError(w, http.StatusInternalServerError, "internal", "内部错误")
		return
	}
	// 保留当前会话，作废其它会话
	if p.Session != "" {
		_ = h.deleteOtherSessions(r.Context(), hashSessionHex(p.Session))
	}
	h.audit(actorString(p), "password_change", "", "ok", ip)
	httpx.WriteOK(w, map[string]any{})
}